This stamp was issued in 1962 to honour the 50th anniversary of the Girl Scouts of America.
Scouting seems to be a very popular subject for stamps. In 2007, because of the 100th anniversary of scouting, this was the theme of the EUROPA stamps. If you feel curious, you can see here the great variety of stamps issued.
I have received, at least, two more stamps, featuring girls and boys: